CN101573985A - Method and apparatus for video predictive encoding and method and apparatus for video predictive decoding - Google Patents

Abstract

Provided are a method and apparatus for video predictive encoding and decoding in which a predictive value of a current block is generated by using, as a motion vector of the current block, a motion vector generated by motion estimation for an adjacent area located in the vicinity of the current block . A motion vector to be used for motion compensation for a current block can be determined by using motion estimation of a previously processed neighboring area without separately transmitting motion vector information on the current block, thereby reducing the number of bits generated during encoding.

Description

Method and device for video predictive coding and method and device for video predictive decoding

technical field

Methods and apparatus consistent with the present invention relate generally to video predictive encoding and decoding, and more particularly to video predictive encoding and decoding in which the The motion vector is used as the motion vector of the current block to generate the prediction value of the current block.

Background technique

In video coding, compression is performed by eliminating spatial and temporal redundancy in a video sequence. In order to eliminate temporal redundancy, by using the picture before or after the current coded picture as a reference picture, and searching for an area similar to the area of the current picture to be coded in the reference picture, detecting the area of the current picture and the found area of the reference picture The amount of motion between them, and encoding the residual between the predicted image obtained by motion compensation based on the detected amount of motion and the current image to be encoded.

In general, the motion vector of the current block has a close correlation with the motion vectors of neighboring blocks. For this reason, in conventional motion estimation and compensation, it is possible to predict the motion vector of the current block from the motion vectors of neighboring blocks and encode only the true motion vector of the current block (which is generated by motion estimation with respect to the current block) The difference between the predicted motion vectors obtained for the blocks reduces the number of bits to be coded. However, also in this case, data corresponding to the difference between the real motion vector and the predicted motion vector must be encoded for each block subjected to motion estimation encoding. Therefore, there is a need for a way to further reduce the number of generated bits by efficiently performing predictive encoding on a current block.

Contents of the invention

The present invention provides a method and apparatus for video predictive encoding and decoding, in which motion information on neighboring regions located in the vicinity of the current block is used to generate a prediction value of the current block without separately transmitting the motion information on the current block, The amount of information generated during video encoding is thereby reduced.

Beneficial effect

According to an exemplary embodiment of the present invention, it is possible to determine a motion vector to be used for motion compensation of a current block by performing motion estimation using a previously processed neighboring area without separately transmitting motion vector information on the current block, thereby reducing the Amount of bits produced during encoding.

Description of drawings

1 is a diagram explaining a process of performing motion compensation on a current block using a video predictive encoding method according to an exemplary embodiment of the present invention;

2 is a block diagram of a video predictive encoding device according to an exemplary embodiment of the present invention;

3 is a flowchart of a video predictive encoding method according to an exemplary embodiment of the present invention;

4 is a diagram explaining a process of performing predictive encoding on a current frame using a video predictive encoding method according to an exemplary embodiment of the present invention;

5 illustrates a processing order of processing blocks using a video predictive encoding method according to an exemplary embodiment of the present invention;

FIG. 6 is a diagram explaining a process of performing predictive encoding on a block subsequent to the current block shown in FIG. 4 according to an exemplary embodiment of the present invention;

FIG. 7 is a diagram explaining a process of performing predictive encoding on a block subsequent to the block shown in FIG. 6 according to an exemplary embodiment of the present invention;

8 is a block diagram of a video predictive decoding device according to an exemplary embodiment of the present invention;

FIG. 9 is a flowchart of a video predictive decoding method according to an exemplary embodiment of the present invention.

Detailed ways

According to an aspect of the present invention, a video predictive coding method is provided. The method comprises: determining a motion vector indicating a corresponding area of a reference frame similar to the adjacent area of the current block by performing motion estimation using an adjacent area located in the vicinity of the current block to be encoded; using the determined adjacent area A motion vector of the region is obtained from the reference frame to obtain a prediction block of the current block; and a difference between the obtained prediction block and the current block is encoded.

According to another aspect of the present invention, a video predictive encoding device is provided. The apparatus includes a motion estimation unit that determines a motion vector of a neighboring area of the current block to be encoded by performing motion estimation using the neighboring area located in the vicinity of the current block, wherein the motion vector indication of the neighboring area is identical to the a corresponding area of a reference frame whose adjacent area is similar; a motion compensation unit that obtains a predicted block of the current block from the reference frame using the determined motion vector of the adjacent area; and a coding unit that encodes the obtained predicted block with The difference between the current blocks.

According to still another aspect of the present invention, a video predictive decoding method is provided. The method includes identifying the prediction mode of the current block to be decoded by reading prediction mode information included in the input bitstream; if the prediction mode indicates that the current block is predicted using motion vectors of neighboring regions located in the vicinity of the current block , then the motion vector indicating the corresponding area of the reference frame similar to the adjacent area is determined by performing motion estimation using the adjacent area of the current block; the current block is obtained from the reference frame using the determined motion vector of the adjacent area a prediction block of the block; and adding the prediction block of the current block and a difference between the current block and the prediction block included in the input bitstream, thereby decoding the current block.

According to another aspect of the present invention, a video predictive decoding device is provided. The apparatus includes: a prediction mode identification unit, which identifies the prediction mode of the current block to be decoded by reading the prediction mode information included in the input bitstream; a motion estimation unit, if the prediction mode indicates that the current block uses If the motion vector of a nearby neighboring area is predicted, it determines the motion vector indicating the corresponding area of the reference frame similar to the neighboring area by using the neighboring area of the current block to perform motion estimation; the motion compensation unit uses The determined motion vector of the neighboring area obtains the prediction block of the current block from the reference frame; and the decoding unit adds the prediction block of the current block and the difference between the current block and the prediction block included in the input bitstream , thus decoding the current block.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that like reference numbers refer to like components shown in one or more figures. In the following description of exemplary embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted for conciseness and clarity.

FIG. 1 is a diagram explaining a process of performing motion compensation on a current block using a video predictive encoding method according to an exemplary embodiment of the present invention. In FIG. 1, '120' indicates the current block to be encoded, '110' indicates the previous area consisting of blocks that have been encoded and subsequently reconstructed before the current block 120, and '115' indicates the adjacent area, which is included in the previous area 110 and located near the current block 120 .

In the prior art, a motion vector is generated by performing motion estimation on the current block 120, and the difference between the generated motion vector and the average or median value of the motion vectors of adjacent blocks located in the vicinity of the current block 120 is encoded. is the motion vector information of the current block 120 . In this case, however, the difference between the true motion vector and the predicted motion vector has to be coded for each block to be motion compensation coded and then has to be transmitted to the decoder.

In an exemplary embodiment of the present invention, the motion vector MVn generated by motion estimation of the neighboring area 115 is used as the motion vector MVc of the current block 120 without motion estimation of the current block 120 . In an exemplary embodiment of the present invention, the corresponding region 160 of the reference frame 150 indicated by the motion vector MVc of the current block 120 is used as a predictor (or predictive block) of the current block 120 . When the motion vector MVn of the neighboring area 115 is used as the motion vector MVc of the current block 120, the decoder can use the result of performing motion estimation on the neighboring area 115 to generate the motion vector MVn of the neighboring area 115, and then use the generated The motion vector MVn of the neighboring area 115 of the current block 120 is used as the motion vector MVc of the current block 120 to perform motion compensation without receiving motion information about the current block 120 (ie, the difference between the motion vector of the current block 120 and the predicted motion vector).

FIG. 2 is a block diagram of a video predictive encoding device 200 according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the device 200 for video predictive coding includes a motion estimation unit 202, a motion compensation unit 204, an intra prediction unit 206, a transformation unit 208, a quantization unit 210, a rearrangement unit 212, an entropy coding unit 214, and an inverse quantization unit. 216 , an inverse transform unit 218 , a filter unit 220 , a frame memory 222 and a control unit 225 .

The motion estimation unit 202 divides the current frame into blocks of a predetermined size, performs motion estimation on a neighboring area that has been previously encoded and then reconstructed, and outputs a motion vector of the neighboring area. For example, referring again to FIG. 1 , the motion estimation unit 202 performs motion estimation on the neighboring region 115 that has been encoded and reconstructed prior to the current block 120 and is subsequently stored in the frame memory 222, thereby generating a corresponding region 155 indicative of the reference frame 150 ( It is the motion vector MVn of the region most similar to the neighboring region 115 of the current frame 100 ). Here, the adjacent area means an area including at least one block that has been encoded and reconstructed before the current block. According to a raster scan method, the adjacent area may include at least one block located above or to the left of the current block. The size and shape of the neighboring region can be varied as long as it allows the neighboring region to include blocks that have been coded and then reconstructed before the current block. However, in order to improve the prediction accuracy for the current block, it is preferable that the adjacent area is immediately adjacent to the current block and has a small size.

The motion compensation unit 204 sets the motion vector of the adjacent area generated by the motion estimation unit 202 as the motion vector of the current block, obtains the data of the corresponding area of the reference frame indicated by the motion vector of the current block, and generates the current block using the obtained data The predicted value of , thereby performing motion compensation. For example, referring again to FIG. 1 , the motion compensation unit 204 sets a vector having the same direction and magnitude as the motion vector MVn of the neighboring area 115 of the current block 120 as the motion vector MVc of the current block 120 . The motion compensation unit 204 also generates the corresponding region 160 of the reference frame 150 indicated by the motion vector MVc of the current block 120 as the predictor of the current block 120 .

The intra prediction unit 206 performs intra prediction on the predicted value of the current block by searching the current frame.

Once the prediction block of the current block is generated by inter-frame prediction, intra-frame prediction, or motion compensation using the motion vector of the adjacent area according to an exemplary embodiment of the present invention, the error value corresponding to the error value between the current block and the prediction block The residual is generated and transformed to the frequency domain by the transform unit 208 and then quantized by the quantization unit 210 . The entropy encoding unit 214 encodes the quantized residual, thereby outputting a bitstream.

The quantized block data is reconstructed by the inverse quantization unit 216 and the inverse transform unit 218 . The reconstructed data is passed through a filtering unit 220 that performs deblocking filtering, and then stored in a frame memory 222 so as to be used for prediction of the next block.

The control unit 225 controls components of the video prediction encoding device 200 and determines a prediction mode for a current block. More specifically, the control unit 225 compares the overhead between the prediction block generated by inter prediction and the current block, the overhead between the prediction block generated by intra prediction and the current block, and the The overhead between the prediction block and the current block generated by the motion vector generated by the motion estimation of the adjacent area, and the prediction mode with the minimum overhead is determined as the prediction mode of the current block. Here, the overhead calculation can be performed using different overhead functions, such as the Sum of Absolute Difference (SAD) overhead function, the Sum of Absolute Transformed Difference (SATD) overhead function, the Sum of Squared Difference (SSD) overhead function, the Mean of Absolute Difference (MAD) ) cost function, and Lagrangian cost function.

A flag indicating whether each block has been motion compensated using motion vectors of its neighboring regions may be inserted into a header of a bitstream to be encoded according to the video predictive encoding method according to an exemplary embodiment of the present invention. The decoder can identify the prediction mode of the current block to be decoded using the inserted flag, and add the prediction value and the difference included in the bitstream, thereby reconstructing the current block.

FIG. 3 is a flowchart of a video predictive encoding method according to an exemplary embodiment of the present invention.

Referring to FIG. 3 , in operation 310, motion estimation is performed on a neighboring region that has been coded and then reconstructed before the current block to be coded, thereby determining a motion vector of the neighboring region, which indicates the most similar The corresponding region of the reference frame.

In operation 320, the determined motion vector of the adjacent area is set as the motion vector of the current block, and the predicted value of the current block is obtained using data of a corresponding area of the reference frame indicated by the motion vector of the current block.

In operation 330, a bitstream is generated by transforming, quantizing, and entropy encoding the difference between the pixels of the predictor value of the current block and the pixels of the current block, and encoding a motion vector indicating that each block has used its neighboring area The predetermined flags of the are inserted into the bitstream.

4 is a diagram explaining a process of performing predictive encoding of a current frame using the video predictive encoding method according to an exemplary embodiment of the present invention, and FIG. 5 illustrates an order of processing blocks using the video predictive encoding method according to an exemplary embodiment of the present invention. In FIG. 4, '420' indicates a current block, and '415' indicates a neighboring region that has been previously coded before the current block 420 and then reconstructed.

It is preferable, but not necessary, to perform predictive encoding according to an exemplary embodiment of the present invention in units of blocks having the same size as a block size used during transformation, thereby determining a motion vector of a next block using a reconstructed value of a current block . In other words, when predicting an encoded image in units of blocks having the same size as the block size used during transformation, before another block is completed, the residual corresponding to the difference between the current block and the predicted block is transformed and Quantization, and the transformed and quantized current block is reconstructed by inverse transform and inverse quantization for use in the prediction of the next block.

Referring to FIG. 4, if a residual corresponding to a difference between pixels of a current block and pixels of a prediction block is transformed into a frequency domain in units of 4x4 blocks, a 16x16 macroblock can be divided into 4x4 blocks, and can be Predictive encoding according to an exemplary embodiment of the present invention is performed in units of 4x4 blocks. Once the motion vector indicating the corresponding region of the reference frame most similar to the neighboring region 415 is determined by performing motion estimation on the neighboring region 415, motion compensation is performed on the current block 420 using the motion vector of the neighboring region 415 without a separate motion information of the current block 420, thereby generating a prediction block of the current block 420, and encoding the difference between the current block 420 and the generated prediction block.

The size and shape of the neighboring area 415 used to determine the motion vector of the current block 420 may vary. According to the raster scanning method shown in FIG. 5, where the divided blocks 500 are coded in order from left to right and from top to bottom, the adjacent area 415 can have various shapes and sizes as long as they allow the adjacent area 415 to include Blocks that have been processed before the current block 420 and are located above or to the left of the current block 420 .

FIG. 6 is a diagram explaining a process of performing predictive encoding on a block 620 after the current block 420 shown in FIG. 4 according to an exemplary embodiment of the present invention, and FIG. A diagram of a process of performing predictive encoding on a block 720 after the current block 620 shown.

Referring to FIG. 6, when processing the next block 620 of the current block 420 shown in FIG. 4, the adjacent area 415 is also shifted to the right by one block according to the raster scanning method, and the next block 620 is predictively coded using the shifted adjacent area 615.

Referring to FIG. 7, when processing the next block 720 of the block 620 shown in FIG. 6, the adjacent area 715 obtained by shifting the adjacent area 615 shown in FIG. 6 to the right by one block may include blocks that have not yet been processed . In this case, the size and shape of the neighboring area 715 used for predictive coding of the block 720 must be changed so that the neighboring area 715 only includes adjacent areas above or to the left of the block 720 that have already been encoded and reconstructed. piece. As such, since the available neighboring blocks that have been encoded and reconstructed change according to the position of the current block to be encoded, it is desirable but not necessary that the encoder and decoder preset the available neighboring blocks according to the position of the current block. The size and shape of the area. In other words, since the available neighboring blocks can change with the relative position of the current block in the macroblock, the encoder and decoder preset the size and shape of the available neighboring areas according to the position of the current block, thus according to the current block The location of the adjacent area is determined, and the prediction value of the current block is generated without separately transmitting information about the adjacent area.

FIG. 8 is a block diagram of a video predictive decoding device 800 according to an exemplary embodiment of the present invention.

Referring to FIG. 8, a video prediction decoding device 800 according to an exemplary embodiment of the present invention includes an entropy decoding unit 810, a rearrangement unit 820, an inverse quantization unit 830, an inverse transformation unit 840, a motion estimation unit 850, a motion compensation unit 860, an intra prediction Unit 870, and filtering unit 880.

The entropy decoding unit 810 and the rearranging unit 820 receive a bitstream and perform entropy decoding on the received bitstream, thereby generating quantized coefficients. The inverse quantization unit 830 and the inverse transform unit 840 perform inverse quantization and inverse transform on the quantized coefficients, thereby extracting transform coding coefficients, motion vector information, and prediction mode information. Here, the prediction mode may include a flag indicating whether a current block to be decoded has been encoded without separate motion estimation by using a motion vector of a neighboring area according to the video prediction encoding method of an exemplary embodiment of the present invention. As mentioned above, motion estimation is performed on a neighboring area that has been decoded before the current block, and the motion vector of the neighboring area is used as the motion vector of the current block for motion compensation.

When the current block to be decoded is predictively encoded by the video predictive coding method according to the exemplary embodiment of the present invention by using motion compensation of the motion vector of the adjacent area without separate motion estimation, the motion estimation unit 850 passes the Neighboring regions perform motion estimation to determine motion vectors for neighboring regions.

Motion compensation unit 860 operates in the same manner as motion compensation unit 204 shown in FIG. 2 . In other words, the motion compensation unit 860 sets the motion vector of the adjacent region generated by the motion estimation unit 850 as the motion vector of the current block, obtains data of the corresponding region of the reference frame indicated by the motion vector of the current block, and generates the obtained The data of is used as the prediction value of the current block, thereby performing motion compensation.

The intra prediction unit 870 generates a prediction block of the current block using neighboring blocks of the current block that have been decoded before the intra prediction-encoded current block.

The error value D'n between the current block and the predicted block is extracted from the bitstream, and then added to the predicted block produced by the motion compensation unit 860 and the intra prediction unit 870, thereby generating the reconstructed video data uF' n. uF'n passes through the filtering unit 880, thereby completing the decoding of the current block.

FIG. 9 is a flowchart of a video predictive decoding method according to an exemplary embodiment of the present invention.

Referring to FIG. 9, in operation 910, prediction mode information included in an input bitstream is read in order to identify a prediction mode of a current block.

In operation 920, if the prediction mode indicates that the current block is predicted using the motion vector of the adjacent area for predictive encoding and no separate motion estimation is required, motion estimation is performed on the previously decoded adjacent area of the current block, thereby determining the indication and the corresponding The motion vector of the corresponding region of the reference frame most similar to the neighboring region.

In operation 930, the determined motion vector is determined as the motion vector of the current block, and a corresponding region of the reference frame indicated by the determined motion vector of the current block is obtained as a predicted value of the current block.

In operation 940, a prediction value of the current block and a difference between the current block and the prediction value included in the bitstream are added, thereby decoding the current block.

Exemplary embodiments of the present invention can also be implemented as computer readable codes on a computer readable recording medium. The computer readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer readable recording medium include read only memory (ROM), random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage devices. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

While the invention has been shown and described in part with reference to exemplary embodiments, it will be understood by those skilled in the art that forms and modifications may be made therein without departing from the spirit and scope of the invention as defined by the following claims. Various modifications in details.

Claims (14)

1. A method for video predictive coding, the method comprising: determining a motion vector of a neighboring region located in the vicinity of the current block to be encoded by performing motion estimation on the neighboring region, wherein the motion vector of the neighboring region indicates a corresponding region of a reference frame similar to the neighboring region; obtaining a prediction block of the current block from the reference frame using the motion vector of the neighboring region; and Encodes the difference between the predicted block and the current block. 2. The method of claim 1, wherein the step of obtaining the predicted block of the current block comprises: setting the motion vector of the neighboring region as the motion vector of the current block, which has the same magnitude and direction as the motion vector of the neighboring region; and A corresponding area of the reference frame indicated by the motion vector of the current block is determined as a prediction block of the current block. 3. The method of claim 1, wherein the neighboring region includes at least one block that has been encoded and reconstructed prior to the current block. 4. The method of claim 1, further comprising inserting into a given region of the bitstream an identifier indicating that the current block has been coded by using prediction of a motion vector of a neighboring region by encoding the current block with Differences between predicted blocks are generated. 5. A device for video predictive coding, the device comprising: a motion estimation unit that determines a motion vector of a neighboring region located in the vicinity of the current block to be encoded by performing motion estimation on the neighboring region, wherein the motion vector of the neighboring region indicates a reference frame similar to the neighboring region the corresponding area; a motion compensation unit that obtains a prediction block of the current block from the reference frame using the motion vector of the neighboring region; and A coding unit that encodes the difference between the predicted block and the current block. 6. The apparatus according to claim 5, wherein the motion compensation unit sets the motion vector of the adjacent area as the motion vector of the current block, which has the same magnitude and direction as the motion vector of the adjacent area; The corresponding area of the reference frame indicated by the motion vector of the block is determined as the prediction block of the current block. 7. The apparatus of claim 5, wherein the neighboring region includes at least one block that has been encoded and reconstructed prior to the current block. 8. The apparatus of claim 5, wherein the coding unit inserts an identifier indicating that the current block has been coded by using prediction of motion vectors of neighboring regions into a given region of the bitstream by coding the current block The difference with the predicted block is produced. 9. A method for video predictive decoding, the method comprising: identifying the prediction mode of the current block to be decoded by reading the prediction mode information included in the input bitstream; If the prediction mode indicates that the current block has been predicted using a motion vector of a neighboring area located in the vicinity of the current block, the motion vector of the neighboring area is determined by performing motion estimation on the neighboring area, wherein the neighboring area The motion vector of indicates the corresponding region of the reference frame similar to the neighboring region; obtaining a prediction block of the current block from a reference frame using the motion vector of the neighboring region; and A prediction block of the current block and a difference between the current block and the prediction block included in the input bitstream are added, thereby decoding the current block. 10. The method of claim 9, wherein the step of obtaining a prediction block of the current block comprises: setting the motion vector of the neighboring region as the motion vector of the current block, which has the same magnitude and direction as the determined motion vector of the neighboring region; and A corresponding area of the reference frame indicated by the motion vector of the current block is determined as a prediction block of the current block. 11. The method of claim 9, wherein the neighboring region includes at least one block that has been decoded prior to the current block. 12. An apparatus for video predictive decoding, the apparatus comprising: a prediction mode identification unit that identifies the prediction mode of the current block to be decoded by reading the prediction mode information included in the input bitstream; a motion estimation unit that, if the prediction mode indicates that the current block has been predicted using a motion vector of a neighboring region located in the vicinity of the current block, determines the motion vector of the neighboring region by performing motion estimation on the neighboring region, wherein the motion vector of the neighboring region indicates a corresponding region of a reference frame similar to the neighboring region; a motion compensation unit that obtains a prediction block of the current block from a reference frame using the motion vector of the neighboring region; and The decoding unit adds a prediction block of the current block and a difference between the current block and the prediction block included in the input bitstream, thereby decoding the current block. 13. The apparatus of claim 12, wherein the motion compensation unit sets the motion vector of the neighboring area as the motion vector of the current block, which has the same magnitude and direction as the determined motion vector of the neighboring area; and A corresponding area of the reference frame indicated by the motion vector of the current block is determined as a prediction block of the current block. 14. The apparatus of claim 12, wherein the neighboring region includes at least one block that has been decoded prior to the current block.

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